Liquid type air conditioning apparatus and method for marine applications



Sept. 16, 1958 2,852,090

G. A. KELLEY LIQUID TYPE AIR CONDITIONING APPARATUS AND METHOD FOR MARINE APPLICATIONS Filed D90. 31, 1956 INVENTOR. 671.5527- 62 KEZZEY United States Patent LIQUID TYPE AIR CONDITIONING APPARATUS AND lVIETI-IOD FOR MARINE APPLICATIONS Gilbert A. Kelley, Toledo, Ohio, assignor to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio Application December 31, 1956, Serial No. 631,635 11 Claims. (Cl. 183-2) This invention relates to novel apparatus and method for cooling and dehumidifying air.

A conventional conditioning apparatus employing dehumidification and cooling consists of a liquid-cooled coil over which hygroscopic liquid is sprayed. Air is passed down through the coil contained in a passage and up through a second passage containing means for eliminating any hygroscopic liquid carried over. Apparatus of this type is disclosed in a copending application of Kelley et 211., Serial No. 516,928, assigned to applicants assignee.

Where greater cooling and/or dehumidifying is desired, a multiple stage system is necessary. This consists of two or more cooling coils with dehumidifying apparatus coupled with one or more of the coils. The first coil is cooled with water which is usually recirculated through a cooling tower except in locations where the water is relatively inexpensive in which case it may be dispensed with after passing through the coil. The final stage or stages of cooling are accomplished with a refrigeration coil. By cooling the air in the initial stage or stages with water, the cost of cooling is maintained at a minimum.

The desired dew point or relative humidity of the conditioned air usually requires that dehumidifying be done in conjunction with both cooling steps in a twostage system. With dehumidification in the first stage, considerable moisture is removed before the air reaches the refrigeration coil of the second stage. The moisture removed is not, therefore, cooled with the air in the second stage which reduces the heat removing capacity required for the refrigerating coil.

The hygroscopic liquid used in the dehumidification steps is very efiective when sprayed over the coils. Where the two coils are contained within one unit, the hygroscopic liquid is drained from the coils into a single sump. The sump contains regenerated hygroscopic liquid which is initially much hotter than the other liquids drained from the coils. This is true since the hygroscopic liquid is regenerated at 220-250 F. and is returned to the sump at this temperature. The resulting mixture of the hot regenerated liquid, the cool liquid that has passed over the water-cooled coil, and the cold liquid which has passed over the refrigeration coil, has a temperature substantially above that passed over the refrigeration coil. A considerable portion of the heat removal capacity of the refrigeration coil is thus spent in continually cooling the warm liquid passed thereover.

To overcome this disadvantage, the coils may be placed in separate housings through which the air passes in series. Each housing has a separate sump for the hygroscopic liquid received from the respective coil. This apparatus may thus maintain the liquid in the refrigeration coil sump cooler than that in the water coil sump. The apparatus, however, being in two separate housings, requires considerably more space. This is a prime disadvantage where space is at a premium, which includes any crowded quarters, as ships or vehicles. It is also difficult 2 to maintain proper concentration control of the liquid in the two sumps for this type of application and a comparatively complicated control system is required. When used on ships or other moving vehicles, the movement presents special problems that prohibit the use of a two sump system.

In View of these factors, apparatus and a method of operation have been developed that permit the utilization of a single sump with a multiple stage unit employing both refrigerant and water cooling. The unit requires a minimum amount of controls and yet operates in an eificient manner. It combines the physical advantages of a single. sump system with the operating efficiency of a two sump system for many applications.

For further consideration of what is novel and the invention, refer to the following portion of the specification, the depending claims, and the accompanying drawing.

In the drawing:

Figure 1 is a schematic representation of apparatus embodying the invention, and I Figure 2 is a schematic representation of the temperatures and flows involved in the operation of the apparatus of Figure 1.

According to the invention, the conditioning apparatus 11 comprises a first casing 12 and a second casing 13. The first casing contains a Water-cooled coil 14 to which water is supplied through inlet 15 and removed through outlet 16. Casing 13 contains a contactor 17 which comprises a plurality of finned tubes or plates that allow hygroscopic liquid sprayed thereover to intimately contact the air.

A sump 18 is provided to collect hygroscopic liquid which is sprayed by spray bars 20 and 21 over coil 14 and contactor 17 respectively and which drains from sloping surfaces 22 and 23 into the sump. A pipe 24 connects the sump to a pump 25 which supplies the liquid through pipe 26 to spray bar 20 and through pipe 27 to spray bar 21. The latter liquid passes through a heat exchanger 40 which may be in the form of a conventional shell and tube cooler. Refrigerant is also passed therethrough by means of inlet pipe 41 and outlet pipe 42 connected to a refrigerating unit 46. I

A branch pipe 28 leads from pump 25 to a spray bar 3% of regenerator 31 with orifices 47, 48, and 49 being used to regulate flow through pipes 26, 27, and 28 respectively. The regenerator has a coil 32 over which the hygroscopic liquid is sprayed, the coil being supplied steam through inlet 33 and is removed through outlet 34. Outside or scavenger air is passed down through coil 32 by a blower (not shown) to carry away the water vapor removed from the hygroscopic liquid by the heat from the steam. The regenerated liquid is collected by sump 35 and drained back to sump 18 through drain pipe 36. The steam may be supplied coil 32 at a constant rate or it may be controlled in a conventional manner by an adjustable valve 37 at the inlet which is controlled according to the specific gravity of the liquid in sump 18- as measured by instrument 38. It may also be controlled according to the liquid level in sump 18. When the specific gravity is below that desired, valve 37 will be further opened to supply more steam to coil 32 and further concentrate the solution. When the specific gravity is above that desired the opposite will occur.

In the operation of the apparatus, air is drawn through duct 48v from the space which is being conditioned. A blower 39 is placed in outlet duct 44 for this purpose. The air is cooled by coil 14 and dehumidified by the hygroscopic liquid sprayed relatively warm, tends to heat the air and counteract the cooling effect of the water. The air then passes up over it. This liquid, being tioned space.

In a typical marine application, 7000 C. F. M. of air enters the unit at 95 F. dry bulb and 77 F. dew point with 140 grains/lb. of moisture. After passing through coil 14 and being contacted with the hygroscopic liquid, the air will be at approximately the same dry bulb tem perature but with grains/ lb. of moisture. In this case,

sea water for coil 14 enters at 85 F. whose cooling tendency is partially counterbalanced by the heated hygroscopic liquid which is at a temperature of 106 F. This is so because the regenerated liquid enters sump 18 from regenerator 31 at approximately 225 F. which, although small in volume, is suificient to maintain the mixture in the sump at 106 F. in spite of the cooler liquid from coil 14 and contactor 17. The air then passes through contactor 17 which produces a temperature of the air at outlet duct 44 of approximately 60 F. dry bulb with a dew point of 20 F. and 15 grains/lb.

The flow of hygroscopic liquid, a 42% aqueous solution of lithium chloride, and temperatures thereof are shown in the schematic representation of Figure 2. The liquid in the sump is pumped to the regenerator at a sufficient rate so that 60#/min. of the regenerated liquid will flow back to the sump at 225 F. A sufficient quantity is also pumped from the sump over the first stage coil to return 360#/ min. of the diluted liquid to the sump at 95 F. Likewise, a suflicient quantity is passed over the second stage contactor to return 300#/Inin. of the diluted liquid to the sump at 95 F.

The temperature of theair leaving coil 14 will be equal to the temperature of the liquid that has passed over the coil, in this case 95 F. This is substantially true for a wide range of flow of the hygroscopic liquid since the temperature of the water entering the coil at inlet 15 will be constant and tends to maintain the term peratures of the air and hygroscopic liquid constant.

With the external cooling of the liquid sprayed over contactor 17, however, the liquid begins to warm up immediately upon contacting the air and continues to do so until it leaves the contactor surface. Its temperature must at least equal that of the liquid leaving coil 14, as will be subsequently explained, and depends on the temperature differential of the air and liquid, the quantity of the liquid, and the length of time the liquid is in contact with the air. The temperature of the air leaving coil 14 is fixed and the temperature of the liquid sprayed over contactor 17 is predetermined according to the final temperature desired for the conditioned air. The quantity of hygroscopic liquid sprayed over the contactor must be sufficient to wet the entire cross-sectional area of the contactor. Therefore, of the aforementioned three factors, the only variable one is the length of time in which the liquid contacts the air. This may be regulated by the depth of the contactor. For instance, in the present case, 18 rows of finned tubes with a 2" diameter are used to assure that the minimum quantity of the liquid sprayed over the contactor attains the temperature of the air, namely 95 F.

As previously stated, it is important to have the temperature of the liquid leaving contactor 17 at least as high as that leaving coil 14. This is necessary to obtain maximum efiiciency of the refrigeration and is a feature of the invention. It is, of course, possible and permissible to have the temperature of the former higher than that of the latter because of the latent heat of condensation of moisture absorbed in the liquid. However, if the temperature of the contactor liquid were below that of the liquid leaving the coil, the cooler liquid from contactor 17would cool the liquid in sump 18 to a greater extent and hence the liquid sprayed over coil 14 would be cooler. The refrigerant would thus take over part of the load of the cooling water and not be used in the most eflicient manner.

To illustrate this, in the present case, the water-cooled coil must remove 427,000 B. t. u./hr. due to the latent heat of the moisture, grains/1b., removed from the air in passing over the coil. The water need only remove 151,000 B. t. u./hr. in cooling the hygroscopic liquid from 106 F. to F., the total heat load thereon thus being 578,000 B. t. u./hr. If the apparatus is changed, for example by substituting a smaller contactor for that previously described, so that the hygroscopic liquid leaving the contactor is cooler than that leaving the coil, say 80 F. instead of 95 F., the temperature of the liquid in the sump will be 99.5 F. The heat load carried by the coil will be decreased by 89,200 B. t. u./hr., (151,000)(l0699.5)/(106-56), or 15.2%. On the other hand, the heat removal capacity of the liquid sprayed over the contactor will be decreased '(95-80)/ (95-56) or 38.5%. This single change decreases the heat removal capacity of the liquid sprayed over the contactor and also decreases the actual heat load of the water-cooled coil by 89,200 B. t. u./hr.

Another feature of the invention lies in the external cooling of the hygroscopic liquid rather than in conventional internal cooling as by a refrigerant cooled coil in casing 13. With the flow of air passing up through this casing, the new method gives the maximum cooling eiiect. If a conventional coil were used, the hygroscopic liquid would be at its lowest temperature at the bottom of the coil after passing thereover. The air would thus be subjected to the lowest temperatures at the bottom of the coil and the highest temperatures at the top of the coil, a condition opposite to that desired. With the new method of cooling, the hygroscopic liquid is at its lowest temperature at the top of the contactor and at its highest temperature at the bottom as it falls through the ccntactor and is warmed by the air. This condition achieves the maximum cooling effect.

The invention basically comprises a two-stage c0nditioner which has a water cooled coil and a contactor surface, the air flowing down through the coil and up through the contactor. The contactor is of suflicient depth that the hygroscopic liquid sprayed over the coil is warmed by the air sufficiently to be at least substantially at the same temperature, upon leaving the contactor, as that of the liquid leaving the water cooled coil. Also, the hygroscopic liquid sprayed over the contactor is initially cooled by means of a heat exchanger located externally from the casing containing the contactor.

The disclosure is intended to serve in an illustrative and not a limiting sense, the invention being defined and limited only by the appended claims.

I claim:

1. A method for conditioning air which comprises passing air to be conditioned through a first enclosed zone and then through a second enclosed zone, circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through the first enclosed zone in contact both with the air passing therethrough and with a cooled surface disposed therein, and back into the sump, cooling the first stream of hygroscopic liquid, by heat transfer to the cooled surface, to a temperature of X, which temperature is lower than that at which the stream leaves the sump, and returning the first stream to the sump at such lower temperature, circulating a second stream of the hygroscopic liquid from the sump, through a heat exchanger wherein the second stream is cooled to a temperature lower than X, and then through the second enclosed zone and back into the sump, warming the second stream of hygroscopic liquid, while within the second enclosed zone, and by the combined elfects of the heat of absorption of water vapor therein and of heat transfer with the air being conditioned, to a temperature which isat least as high as X, and returning the second stream to the sump while substantially at the temperature Y, delivering a third stream of the hygroscopic liquid from the sump to a regenerator, and returning a stream of a concentrated hygroscopic liquid from the regenerator to the sump, whereby the air delivered from the second enclosed zone is conditioned to a predetermined temperature and moisture content.

2. A method for conditioning air which comprises passing air to be conditioned through a first enclosed zone and then through a second enclosed zone, circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through the first enclosed zone in contact both with the air passing therethrough and with a cooled surface disposed therein, and back into the sump, cooling the first stream of hygroscopic liquid, by heat transfer to the cooled surface, to a temperature of X, which temperature is lower than that at which the stream leaves the sump, and returning the first stream to the sump at such lower temperature, circulating a second stream of the hygroscopic liquid from the sump, through the second enclosed zone and back into the sump, transferring heat from the second stream to maintain the temperature thereof lower than X on the hygroscopic liquid inlet side of the second enclosed zone, warming the second stream of hygroscopic liquid, while within the second enclosed zone, and by the combined efifects of the heat of absorption of water vapor therein and of heat transfer with the air being conditioned, to a temperature which is at least as high as X, and returning the second stream to the sump while substantially at the temperature Y, delivering a third stream of the hygroscopic liquid from the sump to a regenerator, and returning a stream of a concentrated hygroscopic liquid from the regenerator to the sump, whereby the air delivered from the second enclosed zone is conditioned to a predetermined temperature and moisture content.

3. A method for conditioning air which comprises passing air to be conditioned through a first enclosed zone and then through a second enclosed zone, circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through the firstenclosed zone in contact both with the air passing therethrough and with a cooled surface disposed therein, and back into the sump, cooling the first stream of hygroscopic liquid, by heat transfer to the cooled surface, to a temperature of X, which temperature is lower than that at which the stream leaves the sump, and returning and first stream to the sump at such lower temperature, circulating a second stream of the hygroscopic liquid from the sump, through a heat exchanger wherein the second stream is cooled to a temperature lower than X, and then through the second enclosed Zone and back into the sump, wanning the second stream of hygroscopic liquid, while within the second enclosed zone, and by the combined efiects of the heat of absorption of water vapor therein and of heat transfer with the air being conditioned, to a temperature which is at least as high as X, and returning the second stream to the sump while substantially at the temperature Y, whereby the air delivered from the second enclosed zone is conditioned to a predetermined temperature and moisture content.

4. A method for conditioning air which comprises passing air to be conditioned through a first enclosed zone and then through a second enclosed zone, circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through the first enclosed zone in contact both with the air passing therethrough and with a cooled surface disposed therein, and back into the sump, cooling the first stream of hygroscopic liquid, by heat transfer to the cooled surface, to a temperature of X, which temperature is lower than that at which the stream leaves the sump, and returning the first stream to the sump at such lower temperature, circulating a second stream of the hygroscopic liquid from the sump,

through the second enclosed zone and back into .the sump, transferring heat from the second stream to maintain the temperature thereof lower than X on the hygroscopic liquid inlet side of the second enclosed zone, warming the second stream of hygroscopic liquid, while within the second enclosed zone, and by the combined effects of the heat of absorption of watervapor therein and of heat transfer with the air being conditioned, to

a temperature which is at least as high as X, and'returning the second stream to the sump while substantially at the temperaure Y, whereby the air delivered from the second enclosed zone is conditioned to a predetermined temperature and moisture content.

. 5. A method for conditioning air which comprises circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through a first enclosed zone in contact with a cooled surface disposed therein and back into the sump, circulating a second stream of the hygroscopic liquid from the sump, through a second enclosed zone and back into the sump, transferring heat from the second stream to a coolant before the second stream is returned to the sump, delivering a third stream of the hygroscopic liquid from the sump to a regenerator, returning a stream of a concentrated hygroscopic liquid from the regenerator to the sump, passing air to be conditioned through the first enclosed zone and then through the second enclosed zone, in contact and in heat exchange relationship with the streams of hygroscopic liquid flowing through the zones, and so regulating the various rates of fluid flow and of heat transfer that the first stream of hygroscopic liquid is cooled from the temperature at which it leaves the sump to a lower temperature of X, at which lower temperature it is returned to the sump, while the second stream of hygroscopic liquid absorbs heat from the air being conditioned, and dehumidified air at a predetermined temperature is delivered from the second enclosed zone, and the second stream is returned to the sumpat a temperature at least as high as X. i v

6. A method for conditioning air which comprises circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through a first enclosed zone in contact with a cooled surface disposed therein and back into the sump, circulating a second stream of the hygroscopic liquid from the same sump, through a heat exchanger wherein the second stream is cooled, and then downwardly through a second enclosed zone which is independent from the heat exchanger, and back into the sump, delivering a third stream of the hygroscopic liquid from the sump to a regenerator, returning a stream of a concentrated hygroscopic liquid from the regenerator to the sump, and passing air to be conditioned through the first enclosed zone and then through the second enclosed zone, in contact and in heat exchange relationship with the streams of hygroscopic liquid flowing through the zones, all of the cooling of air in the second zone being afiected by said second stream.

7. A method for conditioning air which comprises circulating a first stream of a hygroscopic liquid from a sump containing a body thereof, through a first enclosed zone in contact with a cooled surface disposed therein and back into the sump, circulating a second stream of the hygroscopic liquid from the sump, through a second enclosed zone and back into the sump, transferring heat from the second stream to a coolant before the second stream is returned to the second enclosed zone on its way to the sump, delivering a third stream of the hygroscopic liquid from the sump to a regenerator, returning a stream of a concentrated hygroscopic liquid from the regenerator to the sump, and passing air to be conditioned through the first enclosed zone and then through the second enclosed zone, in contact and in heat exchange relationship with the streams of hygroscopic liquid flowing through the zon'es,-the flow of air in the second zone being countercurrent to the flowof solution therein.

8. Apparatus for conditioning air comprising a first conditioning chamber, a cooling member disposed in said first chamber, a second conditioning chamber, means for establishing a flow of air to'be conditioned through said first-chamber and thenupwardly through said second chamber, heat exchange means effective to cool a hygroscopic liquid flowed therethrough, a sump containing a body of a hygroscopic liquid, means for circulating a first stream'of the hygroscopic liquid from said sump, through said first chamber, in contact with said cooling member and with air within said chamber, and back into said sump, means for circulating a second stream of the hygroscopic liquid from said sump, through said heat exchange means, then gravitationally downward through said second chamber, in contact with air within said chamber, and back intosaid sump. l

9. Apparatus for conditioning air comprising a first conditioning chamber, a cooling member disposed in said first chamber, a second conditioning chamber, means for establishing a flow of air to be conditioned through said first chamber and then upwardly through said second chamber, a sump containing a body of a hygroscopic liquid, means for circulating a first stream of the hygroscopic liquid from said sump, through said first chamber, in contact with said cooling member and with air Within said chamber, and back into said sump, means for circulating a second stream of the hygroscopic liquid from said sump downwardly, through said second chamber, in contact with air within said chamber, and back into said sump, means positioned upstream, relative to the flow of the second stream, from the return thereof to the sump for transferring heat from the second stream of hygroscopic liquid, a regenerator, means for delivering a third stream'of the hygroscopic liquid from said sump to said regenerator, and means for returning a concentrated hygroscopic liquid from said regenerator to said sump.

10. Apparatus for conditioning air comprising a first conditioning chamber, a cooling memberdisposed in said first chamber, a second conditioning chamber, means 'for establishing a flow of air to be conditioned through said first" chamber and then upwards through said second chamber, a sump containing a body of a hygroscopic liquid, means for 'circulating a first stream of the hygroscopic liquid from said sump, through said firstchamber, in contact with said cooling member and with air within said chamber, and back into said sump, means for circulating a second stream of the hygroscopic liquid from said sump, downwards through said second chamber, in contact with air within said chamber, and back into said sump, and means positioned upstream, relative to the flow of the second stream, from the return thereof to the sump for transferring heat from the second stream of hygroscopic liquid before contacting therewith the air in the second chamber. i

11. Apparatus for conditioning air comprising a first conditioning chamber, a cooling member disposed in said first chamber, a second conditioning chamber, acontactor within said second chamber, means for establishing a flow of air'to be conditioned through said first chamber and then upwardly through said second chamber, 'heat exchange means effective to cool a hygroscopic liquid flowed therethrough, a sump containing a body of a hygroscopic liquid, means for circulating a first stream of the hygroscopic liquid from said sump, through said first chamber, in contact with said cooling member and with air within said'chamber, and back into said sump, means for circulating aseco'nd stream of the hygroscopic liquid from said sump, through said heat exchange means, then through said second chamber, over said contactor, and in counter-current flows contact with air within said chamber, and back into said sump.

References Cited in the file of this patent UNITED STATES PATENTS 2,280,633 Crawford i Apr. 21, 1942 

